I don't need to pause the computer but to rather pause the execution of the program (something that event.pull in Lua can do). Returning false or throwing an error is a bit of a breaking API change and differs from the ComputerCraft approach, so I'd prefer to not use it. However, it could be a good idea to send a signal either way to allow catching it, but I'd still need to enforce the limit by waiting a certain amount of time in the callback.